Such a piston arrangement is known from U.S. Pat. No. 2,451,216. Here, the piston head has an axially inwards extending projection with a spherical recess, in which the ball is supported. In an alternative embodiment, the spherical design is formed by a sheet metal element, which is inserted in the piston. Such a piston must be usable for a domestic refrigerator.
The connection between a piston and a connecting rod by means of a ball joint is also known from DE 25 10 957 A1. Here, the ball is held in the piston by a ball cup, which is made of a plastic material, which is sprayed or moulded onto the ball head.
JP 01-141274 A shows a further ball joint connection in a piston of a compressor, in which the ball is located in a recess in the piston head. The ball is held by a spring, which has passage openings for the entry of lubricating oil into the bearing surfaces.
JP 63-029075 A2 shows a similar embodiment, in which the piston head is made to be relatively thick. The piston head has a spherical recess, in which the ball is supported. The ball is held in the piston by a spring, which engages behind a circumferential projection.
When using such a piston arrangement in compressors, which are used for refrigeration units, it is endeavoured to keep the costs of manufacturing small.
It is an object of the present invention to improve upon or overcome the problems associated with the prior art.